• State Resolved
  • Locked Locked
  • Replies 1 reply
  • Subscribers 46 subscribers
  • Views 657 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

ADS1261: vs ADS124S08

Darren (FAE)
Expert 5483 points

Part Number: ADS1261
Other Parts Discussed in Thread: ADS124S08

I am hoping someone can help me with the main differences between these devices for use in temperature measurement applications... (RTD, thermistors, thermocouples)

Apart from the fact they have a different number of channels, and data rates, are there any reasons you would chose one over the other?

I looked at gain / offset / INL error & drift, and everything is basically within the ballpark of each other except for the gain error. (ADS1261 has a MAX gain error of ±0.5%FSR, while the ADS124S08 is 200ppmFSR MAX (0.02%FSR) I also tried to make sure the comparison was with MAX PGA setting (128) for each comparison.

Both have INL error of around 0.001%FSR, so really error is dominated by gain / offset error & drift.

Since offset / gain error can be calibrated out, linearity doesn't seem like a big difference / concern....?

I noticed that the ADS1261 has an internal sampling frequency of Fclk / 8, so around 1MHz, compared to the ADS124S08.

Is my understanding that, for the same number of SPS (say 50SPS), because the ADS1261 sampling frequency is faster, the oversampling ratio is better, leading to noise being better averaged out?

The TI.com 1ku price is >$6 for the ADS1261, while it is still around $4.5 for the ADS124S08...

The internal reference seems worse for the ADS1261 as well (initial accuracy is 0.2% vs ADS124S08 MAX of ±0.05%, and max temp drift for ADS1261 reference is 40ppm/℃, while it is only MAX 10ppm/℃ for ADS124S08...

I could go on, but I am having trouble understanding the benefit...is it just the cost of implementing a higher sampling rate w/ the ADS1261 that drives the price up $1.5 more than the ADS124S08, even with less channels?

The requirement for temp measurement is roughly <50ms / channel output sampling speed...

I am trying to understand why you would select one over the other for a temperature sensing module...

Any guidance appreciated!

Regards,

Darren

  • 0
    TI__Guru 58861 points

    Hi Darren,

    The main differences between the ADS124S08 and ADS1261 are as follows:

    • ADS1261 (40-kSPS) has a faster max sampling rate compared to ADS124S08 (4-kSPS)
    • ADS1261 is lower noise compared to ADS124S08
    • ADS124S08 (12) has more channels compared to ADS1261 (10)
    • ADS124S08 is lower power compared to ADS1261

    As you noted, many of the other specifications and features are similar between these two devices, but it is really the higher data rate and lower noise that differentiates the ADS1261 from the ADS124S08. In certain temperature measurement application where channel scan time is critical, the ADS1261 could be a better fit. Or, if many input channels were required, the customer might choose the ADS124S08 instead.

    I hope this helps you choose the correct ADC. If you have additional questions, please let me know

    -Bryan